MIXED CEOP OF TATlIorS AGES. 91 



1874 and 1875, sporadically in 1876, and again gregariously in 

 1877. As a rule, the individuals that ilower thus sporadically are 

 among those which possess the least vital energy (this seems espe 

 cially to be the case with Dendrocalamus strictus). Such indivi- 

 duals are usually the older ones. Hence it is an advantage for a 

 species, which seeds only at long intervals, to be represented by at 

 least a few old trees that are not prevented by extraneous circum- 

 stances from flowering and bearing fruit. 



(c) Season of fall of seed. — -Individuals even of one and the same 

 species flower and ripen and shed their seed at short intervals one 

 after another, never all together, so that, unless the entire season 

 of vegetation is unfavourable for germination, some seeds are bound 

 to be shed at the right moment. This absence of simultaneousness 

 is, in addition to other causes, due also to a difiference of ages. Hence 

 the presence of representatives of different ages increases the chances 

 of a more or less considerable number of seeds of every component 

 species falling at a favourable moment and thereupon successfully 

 germinating each time the species in question seeds. 



(d) Relative vitality or germinative power of the seed. — ^As a rule 

 very old or very young trees produce seeds that are either 

 barren or possess very little germinative power. And even if- the 

 seeds are not barren, their vitality is more easily destroyed than 

 that of seeds furnished by vigorous trees of middle age. Hence a 

 species may be weak in numbers, and yet be comparatively strong 

 enough, from being represented chiefly by individuals of middle 

 age, to be able to perpetuate itself in the crop, 



(e) Relative age of fertility. — .The presence of variously aged 

 individuals prevents the more precocious species from enjoying 

 any advantage over the rest. Indeed, it may happen that the for- 

 mer, from being generally represented by very much younger in- 

 dividuals, may be placed at a disadvantage. 



XIII. Relative power of healing oveb wounds. — This 

 will depend to no inconsiderable extent on the ages of the individuals, 

 quite irrespective of the species. Thus advantage in point of age 

 may tell very much in favour of an otherwise less fortunately 

 placed species. 



XIV. Relative facility op bbplaoing lost or damaged 

 AERIAL ORGAjfS. — -Advancing age wall obviously diminish the gene- 

 ral faculty of reproducing lost or injured parts. Hence an abso- 

 lutely strong species in this as well as in many other respects may, 

 simply from being represented by old individuals, ultimately find 

 itself at a disadvantage. 



